Quasi-Solid-State Rechargeable Lithium-Ion Batteries with a Calix[4]quinone Cathode and Gel Polymer Electrolyte

摘要

Rechargeable lithium-ion batteries (LIBs), which are currently based on the exchange of Li/Li~+ between a graphite (Li_xC6) anode and an inorganic lithium-transition-metal-oxide cathode, have been widely used in portable electronics. However, the further application of LIBs in the areas of large-capacity and high-power electronics, electrical vehicles, and smart grids is still limited. Critical issues are the low capacity, low energy/power density, short life, high cost, and low safety of the batteries. Among various strategies, one interesting approach is to find redox-active organic materials with high capacities and low cost.Recently, carbonyl organic compounds, such as Li2C2O6 (C_(theo) = 589mAhg~(-1)) and pyrene-4,5,9,10-tetraone (C_(theo) = 409 mAhg~(-1)) have been considered as promising materials for the cathode of LIBs primarily owing to their high theoretical gravimetric capacities. However, the electrochemical performance of those materials as the cathode of LIBs was always poor because they suffer from severe solubility in liquid organic electrolyte. As an attempt to solve this problem, it is found that grafting a soluble active "monomer" organic molecule to an insoluble inactive substrate, such as SiO2 helps. However, the tested molecule, which is a quinone derivative of calix[4]arene, only has a low theoretical capacity (189 mAhg~(-1)). Moreover, since the ion conduction and transport in electrolyte is so important in electrochemical energy conversion and storage, the solubility problem of organic materials in electrolyte has been effectively mitigated by accommodating soluble qui-nonic cathode materials in quasi-solid-state cells. For example, a capacity exceeding 200 mAhg~(-1) with excellent cyclability has been obtained for tetracyanoquinodimethane (TCNQ)-based all-solid-state cells with a silica room-temperature ionic liquid (RTIL) composite quasi-solid electrolyte. More recently, by using the same electrolyte, a capacity of approximately 300mAhg~(-1) with a power density of 540 Whkg~(-1) has been achieved by 2,5-dihydroxy benzoqui-none (DHBQ)-based solid-state cells.